Two of men’s tennis’ hardest hitters were thrown together in the match which played out 6-7 (1-7), 6-3, 7-6 (7-3) to a full house in London’s O2 Arena shortly after midnight.
Söderling predicted before the match that he would have to be at the top of his game to defeat the talented South American, who many experts tip to be the future world number one.
The Swede came out strong in a tight first set and was forced to defend four break points to level at 6-6.
The early points in the tie-break went Söderling’s way and he was able to gallop away with the first set.
The second set saw Del Potro comeback strongly and win comfortably 6-3.
Despite breaking Del Potro’s serve at 3-2 in the fourth set Söderling then lost his own and the final set also went to a tie-break, which the Argentinian closed out 7-3 on an ace.
Del Petro will face Nikolay Davydenko in Sunday’s final after the Russian stunned world number one Roger Federer in their semi-final with a 6-2, 4-6, 7-5 victory on Saturday.
Federer had never lost to Davydenko in 12 previous meetings, but the Wimbledon and French Open champion was unable to extend that run in the semi-finals at London’s O2 Arena.